Is there any internal data on where students are going instead?
You honestly don't wanna know
If my peers are any indication, a whole lot of TikTok, Reels, Twitter, Discord, and other such mind-numbing platforms.
The types of platforms I would consider 'substantive' (or, at least, more substantive than those platforms) are definitely on the way out.
The few times friends have seen me browsing Hacker News or a certain Mongolian basket weaving form, the first thing they comment on is how confusing the interface is, and how old the site looks.
I truly don't understand the mentality, but if your site doesn't take three seconds to buffer a simple text drop down menu, and have JavaScript elements load in mid-scroll that bump elements around the page making you just barely miss that button you were trying to click, then your site is seen as 'inferior' or 'sketchy'.
Perhaps I've just had a bad sample, but I've experienced a variety of different environments by this point, and by and large, I've seen more people in my generation act in that manner than not.
Perhaps some interest-related Discord servers. Tragically, Discord is just another locked down silo without publicly accessible front on the web.
Not much, but I do ask the youngest founders what their friends read if they don't read HN, and the only consistent answer I hear is Twitter.
(and btw, they do say "twitter")